Storage tanks incidents

Chang Jl and Cheng-Chung L A study of storage tank incident Journal of loss prevention in the process industrbs 2006 19 51 -59... 

Storage tanks should always be closely surrounded by bund walls to contain crude in the event of a spillage incident, such as a ruptured pipe or tank, and to allow fire fighting personnel and equipment to be positioned reasonably close to the tanks by providing protected access. 

Many steel structures - like bridges, storage tanks, and ships - are held together by welds. And when incidents arise from fast fractures or fatigue failures they can often be traced to weaknesses in the welds. The sinking of the Alexander Keilland oil platform in 1980 is an example. 

Incidents involving storage tanks, stacks, pipelines, and pressure vessels have been described in Chapters 5, 6, and 9. This chapter describes some incidents involving other items of equipment. 

A more serious incident occurred at a plant in which ethylene oxide and aqueous ammonia were reacted to produce ethanolamine. Some ammonia got back into the ethylene oxide storage tank, past several check valves in series and a positive pump. It got past the pump through the relief valve, which discharged into the pump suction line. The ammonia reacted with 30 m of ethylene oxide in the storage tank. There w as a violent rupture of the tank, followed by an explosion of the vapor cloud, which caused damage and destruction over a wide area [4],... 

The incidents described could occur in many different types of plants and are therefore of widespread interest. Some of them illustrate the hazards involved in activities such as preparing equipment for maintenance and modifying plants. Others illustrate the hazards associated with widely used equipment, such as storage tanks and hoses, and with that universal component of all plants and processes people. Other incidents illustrate the need for techniques, such as hazard and operability studies, and protective devices, such as emergency isolation valves. 

The autocatalytic exothermic polymerisation reaction exhibited by styrene was involved in a plant-scale incident where accidental heating caused violent ejection of liquid and vapour from a storage tank [1], Polymerisation becomes self-sustaining above 95°C [2], The monomer has been involved in several plant-scale explosions, and must be stored at below 32°C, and for less than 3 months [3], Styrene is a moderately endothermic compound (AH°f (1) +147.7 kJ/mol,... 

In Instone s data (1989) the OSBL equipment most often involved in large losses seems to be storage tanks (14%). Heaters and furnaces are mentioned in 15% of incidents. Pumps, compressors and boilers are involved equally (5% each) in large losses, whereas flares, cooling towers and API separators happen to be quite rarely involved (<1% each). 

A diverse range of chemical process equipment-including reaction vessels, storage tanks, separation equipment, and transfer equipment. Storage and process equipment (excluding chemical reaction vessels) account for over 65 percent of the equipment involved chemical reaction vessels account for only 25 percent. Reactive incidents can result in a variety of consequences, including fire and explosions (42 percent of incidents) as well as toxic gas emissions (37 percent). 

Considerable experience has been gained from past incidents of storage tank fires. API 2021 Management Atmospheric Storage Tanks Fires contains information useful for tank firefighting. 

Maleic anhydride decomposes exothermically, evolving carbon dioxide, in the presence of alkali- or alkaline earth-metal or ammonium ions, dimethylamine, triethylamine, pyridine or quinoline, at temperatures above 150°C [1], Sodium ions and pyridine are particularly effective, even at concentrations below 0.1%, and decomposition is rapid [2], An industrial incident involved gas-rupture of a large insulated tank of semi-solid maleic anhydride which had been contaminated with sodium hydroxide. Use of additives to reduce the sensitivity of the anhydride has been described [3], Accidental transfer of an aqueous solution of sodium 2-benzothiazolethiolate into a bulk storage tank of the anhydride led to eventual explosive destruction of the tank [4],... 

Davie, F.M., etal., Case histories of incidents in heated bitumen storage tanks, J. Loss Prev. Process Ind., 7, No. 3, 217-221, 1994. 

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